1. Field of the Invention
The invention relates to the use of selected emulsifiers having an increased ecological compatibility for the production of fluid dispersed systems which are present either as W/O inverted emulsions comprising a continuous oil phase or as aqueous emulsions containing a dispersed oil phase and which are suitable for the technical application within the field of use of fluid drill-hole treatment agents. Referring to a characteristic example for agents of this kind, the invention is described hereinbelow by way of oil-based and water-based drilling fluids, respectively, and drilling muds formed therewith. However, the field of application of the modification according to the invention of auxiliary liquids of the kind involved here is not limited thereto, while it also includes in particular the areas of spotting fluids, spacers, auxiliary liquids for workover and stimulation and for fracturing.
It is one particular object of the invention to substantially influence the ecological compatibilty of said auxiliary agents which are being worldwide used today by employing selected and, more specifically, ecologically acceptable types of emulsifiers. In its preferred embodiment the invention intends to use said biologically acceptable emulsifiers simultaneously in combination with oil phases having an increased environmental compatibility and especially a biological degradability.
2. Discussion of Related Art
In the area of liquid sweeping systems for rock-drilling to bring-up the removed drill cuttings, the so-called inverted drilling muds are of excellent importance which, based on W/O emulsions, contain a dispersed aqueous phase in the continuous phase. The content of the dispersed aqueous phase usually is within the range of from about 5 to 50% by weight.
However, also known are water-based drilling fluids comprising an emulsified dispersed oil phase (O/W type), the oil content of which may range from some percent to about 50% by weight. O/W emulsion fluids of this kind exhibit a number of considerable advantages over merely water-based fluid systems.
The stabilization of each of the selected dispersion forms requires the use of appropriate emulsifiers either of the W/O type (inverted fluids) or of the 0/W type (emulsion fluids), respectively. Hereto, reference is made to the pertinent literature, for example, G. R. Gray, H. C. H. Darley, "Composition and Properties of Oil Well Drilling Fluids" 4th Edition, Gulf Publishing Cp., Houston, London 1981, especially pages 51, 64 and 320 et seq.
Today the oil phases of drilling fluids of the type described here and comparably composed other drill-hole treatment agents in practice are almost exclusively formed by mineral oil fractions. This involves a considerable environmental pollution, if, for example, the drilling muds directly or via the drilled rock will infiltrate the environment. Mineral oils are only difficult to decompose and are virtually not anerobically degradable at all and, thus, to be rated as long-term pollutants. Nevertheless, even if these oil phases as the main constituent or at least a substantial portion of the drilling fluid make a significant starting point for ecological considerations, an equivalent attention will have to be paid also to the other components of such multi-component systems. Here, the emulsifiers are of specific importance. Compounds of this type, in accordance with the intended use thereof, are highly active substances already at a low concentration which are known to be capable of an intense interaction with the vegetable or animal organism.